The subject disclosure relates to a periodic fluidic ratchet device and a method for forming the same. More specifically, the subject disclosure relates to an electrically conductive deterministic lateral displacement array device and a method for forming the same.
Periodic fluidic ratchets are mechanisms that can separate and/or sort particles in a fluid stream based on size, morphology, and/or mechanical properties of such particles. Periodic fluidic ratchets can comprise lattices of pillar features built into a fluidic channel such that the pillar lattice is off-axis from the channel. The asymmetric orientation of the resulting lattice leads to a selection criterion in which different sized particles are displaced favorably to one side of a pillar or another. A key design feature is the pitch between pillar features which, combined with the pillar feature sizes, defines the gap between such pillar features. The gap size influences the size selection criterion as well as the output performance of the ratchet. Common types of fluidic ratchets are deterministic lateral displacement (DLD) arrays, directional mode locking arrays, and asymmetric slit arrays. DLD systems in particular have been scaled from macroscopic down to the nanoscale (nanoDLD), where the gap sizes approach 10's nanometers (nm) to 100's nm. NanoDLD systems have the potential to separate colloidal material down to 20 nm based only on gap size.
A problem with existing periodic fluidic ratchet devices is that size scaling of the pillar arrays of such devices to achieve smaller particle size selectivity is limited by increasing fluidic resistance, as well as practical issues of fabrication. Another problem with existing periodic fluidic ratchet devices is that size selectivity presents only a single dimension for separation.